Environmental Protection Agency

The U.S. Supreme Court ruled Monday that the Environmental Protection Agency made a mistake when it told electric power plants to reduce mercury emissions. The high court says the EPA should first have considered how much it would cost power plants to do that.

The decision comes too late for most power companies, but it could affect future EPA regulations.

Mercury in the air is a health risk. When you burn coal or oil, you create airborne mercury that can end up in fish we eat and cause serious health problems.

Hundreds of people are expected to testify in Denver on proposed rules to reduce carbon emissions from coal-fired power plants. The Denver hearing is one of several the Environmental Protection Agency is hosting across the country on the plans.